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利用螯合劑搭配超臨界流體萃取土壤重金屬之研究

Extraction of Heavy Metals in Soils with the Supercritical Fluid and Chelating agents

作者:張耀文
畢業學校:輔英科技大學
出版單位:輔英科技大學
核准日期:2013-01-30
類型:Electronic Thesis or Dissertation
權限:Copyright information available at source archive--Fooyin University....

中文摘要

超臨界流體萃取技術是污染處理的新興技術之一。本研究乃利用二氧化碳超臨界流體結合螯合劑以萃取土壤中重金屬。
本研究選用EDTA-2Na及2-囮h甲岸T氟丙酮(2-Thenoyltrifluoroacetone,簡稱TTA)充當金屬螯合劑,實驗發現EDTA-2Na為水相化學物質,與二氧化碳超臨界流體的互溶性不佳,以致萃取土壤中重金屬的效果不理想。而2-囮h甲岸T氟丙酮能與二氧化碳超臨界流體可互溶,因此用以萃取土壤中重金屬的效果較為明顯。
本研究分別比較實驗室製備污染高嶺土與現地污染場址對不同重金屬之去除效果。在實驗室製備污染高嶺土之實驗結果顯示: TTA(2-Thenoyltrifluoroacetone)對重金屬鉛沒有錯合能力。此外,當操作條件為Tc:60℃、Pc:290 atm、TTA濃度0.01M、反應時間30分鐘,實驗顯示重金屬銅、鋅、鎳去除率都可達70%以上。而污染場址之污染土壤的萃取實驗結果則顯示:銅、鋅、鎳的去除效率分別為58.1%、41.4%、31.3%。
研究結果發現:利用二氧化碳超臨界流體結合TTA螯合劑可萃取土壤中的重金屬,且不同金屬離子間有競爭現象。就總萃取質量而言,本萃取方式更適用於多重重金屬污染土壤的處理。
關鍵字:重金屬、超臨界流體、螯合劑、土壤污染

英文摘要

Abstract
Supercritical fluid extraction is one of the new methods of treatment of soil pollutions. In this study carbon dioxide supercritical fluid with chelating agents is used to extract heavy metals from contaminated soils.
The chelating agents used in this research are EDTA-2Na and 2 - thenoyl trifluoroacetone(TTA). It was found that EDTA-2Na aqueous phase chemical substance is so difficult to dissolve in carbon dioxide supercritical fluid that lead extraction ineffective. In addition, TTA can dissolve in carbon dioxide supercritical fluid, and the effect of extraction of heavy metals from contaminated soils is more significant.
In this research, the results of removal of four heavy metals from polluted kaolin prepared in the laboratory were compared to the contaminated site soil. The results show that the lead ions cannot complex with TTA. When the experimental conditions about Tc is 60  C, Pc is 290 atm, the concentration of TTA is 0.01M, reaction time is 30 minutes, the results of removal rate of heavy metals copper, zinc, nickel from polluted kaolin prepared in the laboratory were up to 70% or more. The same treatment apply to contaminated site soil, heavy metals removal efficiency are declined. The removal efficiency of copper, zinc, nickel from contaminated site soil were 58.1%, 41.4%, 31.3%, respectively.
Comparing the impact of different heavy metal ions competing with each other, the removal efficiency showed that Cu > Zn > Ni. For the outlook of extractable metals ion amount, the extract method of carbon dioxide supercritical fluid with chelating agents is more suitable for multi-polluted soils.
Keywords: heavy metals, supercritical fluid, chelating agents, soil pollution


指導教授 - 丁健原

召集委員 - 賈澤民

委員 - 連培榮


 

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